Parse XML response in C#

By using LINQ to XML.

c#

void Main()
{
    XDocument xdoc = XDocument.Parse(@"<tsResponse xmlns='site.com/api' xmlns:xsi='site.org/2001/XMLSchema-instance' xsi:schemaLocation='site.com/api help.site.com/samples/en-us/rest_api/ts-api_3_4.xsd'>
            <credentials token='xxxxxx-xxxxxx-xxxxxx'>
                <site id='xxxxxx-xxxxxx-xxxxxx' contentUrl='sitename'/>
                <user id='xxxxxx-xxxxxx-xxxxxx'/>
            </credentials>
        </tsResponse>");

    XNamespace ns1 = xdoc.Root.GetDefaultNamespace();

    string token = xdoc.Descendants(ns1 + "credentials")
        .FirstOrDefault()?.Attribute("token").Value;

    Console.WriteLine("token = {0}", token);
}

Output

token = xxxxxx-xxxxxx-xxxxxx

If you put the XML string that you get into the variable xmlToParse, you can do:

TsResponse result = _xmlParser.Deserialize<TsResponse>(xmlToParse);

Where _xmlParser is an instance of the class:

using System.Xml.Serialization;

namespace yourNameSpace
{
    public class XmlParser
    {
        public T Deserialize<T>(string input) where T : class
        {
            XmlSerializer ser = new XmlSerializer(typeof(T));

            using (StringReader sr = new StringReader(input))
            {
                return (T)ser.Deserialize(sr);
            }
        }
    }
}

You also need to model the whole XML object as a class in C# (XmlObjects.Credentials in my example) using the for example the page https://json2csharp.com/code-converters/xml-to-csharp which gives you:

// using System.Xml.Serialization;
// XmlSerializer serializer = new XmlSerializer(typeof(TsResponse));
// using (StringReader reader = new StringReader(xml))
// {
//    var test = (TsResponse)serializer.Deserialize(reader);
// }

[XmlRoot(ElementName="site")]
public class Site { 

    [XmlAttribute(AttributeName="id")] 
    public string Id { get; set; } 

    [XmlAttribute(AttributeName="contentUrl")] 
    public string ContentUrl { get; set; } 
}

[XmlRoot(ElementName="user")]
public class User { 

    [XmlAttribute(AttributeName="id")] 
    public string Id { get; set; } 
}

[XmlRoot(ElementName="credentials")]
public class Credentials { 

    [XmlElement(ElementName="site")] 
    public Site Site { get; set; } 

    [XmlElement(ElementName="user")] 
    public User User { get; set; } 

    [XmlAttribute(AttributeName="token")] 
    public string Token { get; set; } 
}

[XmlRoot(ElementName="tsResponse")]
public class TsResponse { 

    [XmlElement(ElementName="credentials")] 
    public Credentials Credentials { get; set; } 

    [XmlAttribute(AttributeName="xmlns")] 
    public string Xmlns { get; set; } 

    [XmlAttribute(AttributeName="xsi")] 
    public string Xsi { get; set; } 

    [XmlAttribute(AttributeName="schemaLocation")] 
    public string SchemaLocation { get; set; } 
}

, then you can go with

result.Credentials.Token

I think that the simplest way is to use LINQ to XML's XDocument:

using System.Xml;
using System.Xml.Linq;

/* ... */

var xml = @"<?xml version='1.0' encoding='UTF-8'?>
<tsResponse xmlns=""site.com/api"" xmlns:xsi=""site.org/2001/XMLSchema-instance"" xsi:schemaLocation=""site.com/api help.site.com/samples/en-us/rest_api/ts-api_3_4.xsd"">
    <credentials token=""xxxxxx-xxxxxx-xxxxxx"">
        <site id=""xxxxxx-xxxxxx-xxxxxx"" contentUrl=""sitename""/>
        <user id=""xxxxxx-xxxxxx-xxxxxx""/>
    </credentials>
</tsResponse>";

var xmlns = XNamespace.Get("site.com/api");
var token = XDocument.Parse(xml)
                     .Element(xmlns + "tsResponse")?
                     .Element(xmlns + "credentials")?
                     .Attribute("token")?
                     .Value;